Nisp (version 2.93.14, 2005-12-29) is a strongly typed dialect of Lisp, implemented as a collection of macros. Older versions of Nisp were based on a tool set called "NILS," but recent versions are based on YTools. (Hence it is referred to in some places as YNisp.) The tar file contains a single directory called ydecl which contains all the type-checking stuff. Y oh Y all these names? Just remember that Nisp = YNisp = YTools + ydecl.